1. Field of the Invention
The present invention relates to a structure of attaching a lighting circuit for an electric discharge lamp in a motorcycle.
2. Description of Related Art
According to Japanese Examined Patent Publication No. Hei 5-32262 entitled "Structure of supporting two-lamp type head lamp of motorcycle etc.", as shown by FIG. 5 of this publication, an attaching stay 34 is extended from a head pipe 13 and head lights 32 are attached to a front end of the attaching stay 34 via connecting plates 40. As seen in this example, it is conventional to extend a stay or a bracket from the body of the motorcycle and attach a head light to the stay or the bracket.
According to an electric discharge lamp which has been adopted in a passenger vehicle in recent years, a large luminous flux number is provided and downsizing of the lamp is facilitated. Therefore, the adoption of this electric discharge lamp has also been studied for use in a motorcycle.
For example, a vehicular head lamp 1 shown by FIG. 1 of Japanese Patent No. 2542962 entitled "Head lamp for vehicle", has an electric discharge lamp 8. Numeral 27 designates a lighting circuit for generating a high voltage power source.
When the stay is forwardly extended and the vehicular head lamp 1 which includes the lighting circuit 27 is attached to the front end of the stay, problems are experienced. For example, the lighting circuit 27 is heavy since it incorporates a transformer or semiconductors for boosting. Accordingly, the stay becomes unnecessarily stout. Therefore, a total weight of the body of the motorcycle is increased, and a moment operating on the body is enlarged when the heavy vehicular head lamp 1 is arranged at a portion remote from the vehicle body.
Therefore, the only alternative includes a heavy lighting circuit 27 attached to a side of the body of the motorcycle on a rear side of the head pipe and the lighting circuit 27 and the electric discharge lamp connected by a high voltage line. However, in addition to the above-mentioned problems, the high voltage line is very long and is therefore located around the handle post of the motorcycle. Therefore, the wiring layout becomes problematic.